1. Field of the Invention
This invention relates to therapeutic appliances and, more particularly, to a transdermal drug-delivery device.
2. State of the Prior Art
Transdermal drug-delivery patches are currently being prescribed for the treatment of various medical problems, such as angina and motion sickness. Advantages of such devices include zero-order delivery or controlled delivery and stoppage of delivery in the event of an adverse reaction; in this case the patient stops delivery of the drug to th body abruptly by removing the device containing the drug reservoir. Depending on the drug, when a transdermal patch or vehicle (e.g. an ointment containing a drug) is removed, the skin may serve as a reservoir for continued delivery of the drug to the body. When the supply of the drug in the device is exhausted, the device is removed and a new one is applied to the skin. Transdermal patches are attached to the skin by means of a pressure-sensitive adhesive layer. Adhesives in current use, however, cling so aggressively that their removal can cause skin irritation and even trauma. To avoid this problem, the next patch is most often applied to a different, but equivalent, area of skin. For a period of time thereafter blood concentrations of the drug can vary anywhere from zero-order to the steady-state blood level. If the new patch is applied to the same area of the skin as that used previously, however, steady-state diffusion already exists and zero-order delivery should continue without interruption.
Since patients who use transdermal delivery patches regularly experience trauma consistently when the patches are removed, understandably, this problem becomes magnified when larger doses are required. In this case, correspondingly larger patches are needed and, of course, cover a more extensive area of skin.
U.S. Pat. No. 3,734,097 discloses a therapeutic adhesive tape of the type previously described which is especially adapted for the treatment of skin lesions.
In U.S. Pat. No. 3,742,951, there is disclosed a bandage for controlled release of medications, such as vasodilators.
U.S. Pat. No. 4,297,995 discloses the use of a two-piece medical bandage employing a post and a base.